Starch is quantitatively the most dominant storage carbohydrate on Earth & is synthesized mostly in plants like corn, potatoes, sweet potato etc. & some cyanobacteria.
Starch consists of amylose & amylopectin having α-1, 4- & α-1, 6-linked glucose units.
The starch molecule accumulates as water-insoluble particles, i.e., the starch granules in the cell of the plants. However, most other species produce water-soluble glycogen as a storage carbohydrate. Both polymers, starch & glycogen are similar in biological function and chemical composition, consisting of glucose units that are linked by α-1, 4 & α-1, 6 glycosidic bonds.
The physical parameters of starch strongly differ from those of glycogen and are responsible for the high value of starch in various applications.
Corn & Potato with Starch Powder
Starch is a versatile biomaterial of special interest due to its abundance, cheapness, non-toxic properties, and biodegradability for various food & non-food industries.
It is widely used in the preparation of numerous dairy & bakery goods, soups, and sauces, as well as coatings and meat products.
Also, there is an increasing demand from non-food industries for starch as a renewable material. Non-food applications of starch encompass pharmaceuticals, textiles, alcohol-based fuels, adhesives, dyes, and furniture.
| Plant Species | Part of plant | Shape of granules | Approx. size of starch granule in µm |
|---|---|---|---|
| Arabidopsis (Arabidopsis thaliana) | Leaves | Discoid | 1 - 2 |
| Potato (Solanum tuberosum) | Tubers | Oval, spherical | 10 - 75 |
| Cassava (Manihot esculenta) | Tubers | Round, irregular | 5 - 40 |
| Maize / Corn (Zea mays) | Grain | Round, polygonal | 5 - 20 |
| Wheat (Triticum spp.) | Grain | Lenticular-shaped, small round | 1.5 - 20 |
| Rice (Oryza sativa) | Grain | Round, angular, and polygonal | 3 - 10 |
| Barley (Hordeum vulgare) | Grain | Large disc-shaped granules, small spherical granules | 1 - 24 |
| Apple (Malus spp.) | Fruit | Spherical or dome-shaped | 2 - 12 |
| Banana (Musa spp.) | Fruit | Elongated ovals with ridges | 14 - 108 |
| Sago (Metroxylon sagu) | Stem | Oval with a temple bell-like shape | 8 - 240 |